The esophagus is a tubular organ that carries food and liquid from the throat to the stomach. It contains muscles that rhythmically contract whenever a person swallows. This contraction generally occurs as a sweeping wave carrying food down the esophagus to the stomach. This sweeping wave of contraction is typically referred to as peristalsis. An upper esophageal sphincter (UES) is located at an upper end of the esophagus. The UES is a muscle that serves as a valve between the esophagus and the pharynx from which the esophagus receives food and liquid when swallowing.
The lower esophageal sphincter (LES) is located at a lower end of the esophagus. The LES is a muscle that serves as a valve between the esophagus and the stomach. The LES protects the lower esophagus from stomach acid and bile, which causes the discomfort of heartburn and in time, can damage or scar the esophagus.
The diaphragm is a muscular membrane that assists is respiration and intersects the upper Gastrointestinal (GI) tract at an approximate right angle, typically within the length of the LES, creating a pressure inversion point (PIP), which is often referred to as the respiratory inversion point (RIP). As used herein, an “upper GI tract” includes at least the UES, esophagus, LES and at least portions of the pharynx and stomach. The PIP is named as such because it is a point along the length of the upper GI tract (typically within, but sometimes distal to, the LES) where the pressure associated with respiration inverts. Above the PIP, pressure decreases during inhalation and increases during exhalation. In contrast, below the PIP, the pressure increases during inhalation and decreases during exhalation. A hiatal hernia occurs if the PIP (i.e., the intersection of the diaphragm and the LES) is not within the LES, but is located below the LES within the upper regions of the stomach.
Manometry is the measurement of pressure. Esophageal manometry measures the muscular pressure exerted along the upper GI tract, for example, during peristalsis. Esophageal manometry is used to evaluate the contraction function of the upper GI tract in many situations (e.g., breathing, swallowing food, swallowing liquid, drinking, coughing, etc.) and can be useful for diagnosing symptoms that originate in the esophagus, for example, difficulty in swallowing food or liquid, heartburn, and chest pain to determine the cause of the symptoms, for example, dysphasia or achalasia.
A variety of esophageal manometry systems have been used to study pressure along the upper GI tract. Such systems typically include a probe that is inserted into the upper GI tract and one or more pressure sensors that detect pressure from different positions within the upper GI tract. One type of a probe is a catheter. An esophageal manometry system that has a catheter as a probe is a referred to herein as a catheter-based esophageal manometry system. Types of catheter-based esophageal manometry systems include solid state systems and water perfuse systems. In water perfuse systems, pressure sensors are located external to the catheter. Each pressure sensor has a corresponding tube that extends into the catheter and pumps fluid (e.g., water) at some longitudinal position of the catheter against the interior surfaces of the GI tract. The pressure resulting from the impact of the fluid against the interior surface is transmitted via the fluid through the tube to the pressure sensor, where it is detected. In contrast, solid state systems do not use fluids, and each sensing element is attached to or embedded within the catheter and detects pressure locally at the point of impact with the interior surface of the upper GI tract. Each sensor transmits its detected values out of the catheter using an electronic or optical signal.
An esophageal manometry system may include or be accompanied by an application (e.g., software, firmware, hardware or a suitable combination thereof) that visually indicates the values detected by the sensors to a user, and may be capable of visually indicating the values detected by the sensor on a temporal representation in real time using a line trace. As used herein, a “temporal representation” is a plot having a temporal dimension representing time, on which values detected over time are visually indicated, concurrently, at temporal positions along the temporal dimension, each detected value visually indicated at a temporal location corresponding to a time at which the value was detected. A temporal representation is useful to concurrently illustrate values of a physical property detected at one or more positions over time.
As used herein, a “line trace” is a visual representation that visually indicates values detected over time at a location on a temporal plot having a temporal dimension corresponding to time. For each location, a baseline for the location running parallel to the temporal dimension is indicated. The value detected at the corresponding position within the region at each time is represented as an offset from the baseline at a temporal location along the temporal dimension that corresponds to the time. The amount of the offset corresponds to the detected value. Each visually indicated value detected at the position may be connected by a continuous line, which, depending on the detected values, may be a straight line or a curved line.
As used herein, a “contour plot” is a visual representation that visually indicates values detected over time at locations on a temporal plot having a temporal dimension corresponding to time and a spatial dimension corresponding to a region. A contour plot may represent to a user pressure data derived from pressure information measured by sensors at a plurality of positions over time. A contour plot may include one or more tones which each represent a pressure range.